1. Field of the Invention
This invention generally relates to integrated circuit (IC) memory devices and, more particularly, to a PCMO thin film with memory properties responsive to crystalline structure.
2. Description of the Related Art
Pr0.3Ca0.7MnO3 (PCMO) metal oxide thin films, which show reversible resistance change responsive to bipolar electrical pulses applied at room temperature, have been grown on both epitaxial YBa2Cu3O7 (YBCO) and partial epitaxial Pt substrates using a pulsed laser deposition (PLD) technique. In U.S. Pat. No. 6,673,691, invented by Zhuang and Hsu, a spin-coat PCMO thin film deposition method is disclosed that results in a PCMO film with reversible resistance characteristics, responsive to unipolar electrical pulses.
The observed change in resistance states is in the range of one to three orders of magnitude. These characteristics make PCMO well suited for use in memory cells and resistor RAM (RRAM) applications. These memory cell devices typically employ at least one electrode made, at least partially, from a noble metal, adjacently located to the PCMO memory resistor material.
There are many methods used for PCMO thin film deposition, such as physical vapor deposition (PVD), metalorganic chemical vapor deposition (MOCVD), and spin-coating. Of the three, spin-coating is one of the best candidates for the large scale manufacturing, as it is a relatively low cost, easy process.
It would be advantageous if the relationship between pulse polarities and PCMO thin film characteristics could be exploited.
It would be advantageous if the pulse polarity needed to change resistance states in a PCMO thin film could be selected in response to properties of the film.